Could probably just route a few pipes below the plants with a small water pump and an aquarium heater and let the convection heat the plants.
It sounds like your problem is not the LEDs, but the COLD. Also if you fill a room with LED or COBS it still gets bloody hot. If you only have a few units hanging it may not heat up as much or at least as quickly. How do you handle night time temps.
So, you grow out in the cold, no insulation, no aircon depending on CO2 burner and HID for heat in the day. Night times you just let shit stretch and freeze? Then you want to blame LED. You see where I'm going.
You are assuming an awful lot here. You must have seen pics of my garden here?
I use a radiator style heater in the 8x9’ room to keep night temps above 64 farenheight. It stays on low. It is a spare bedroom next to my living room.
And the room is using 2 600’s over a 3.5’ x 7’ area. Sometimes I add a 315 LEC if I have a backup in veg.
There would never be enough heat with led to the floor even with the equivalent wattage. I duct the exhaust under the living room in winter.
It goes out the chimney in summer. Heat is not a problem. My bills are extremely low for my output.
I have done all the math and had considered all the parameters I could think of.
And when I build my bigger room in the basement it will be colder down there.
Just the saved propane ruins any electrical savings possible.
Basically both of you have enforced the point that LED is not only more expensive on lighting cost but also all the other infrastructure to go alone with it.
Sure, if you have a 2x4 tent in a room of your home that is already being conditioned by your central HVAC you can probably pop your led up and grow.
For the majority that actually want to pull some weight for the amount of time that's going to be spent tending plants - usually moved to a garage or other non conditioned space, LED posses issues. Unless you are at the perfect geographical location or season of the year.
Basically if you are going big with LED plan to:
Build a FULLY Sealed Insulated Space
C02 supplementation
Ac/Heat control + dehumidification x 10
Basically a lab type environment
On the other have, with HID you can just hang your fixtures and set up an exhaust fan using a small heater at lights out if needed and a dehumidifier.
That is the situation in my garden. If I went LED right now my temps would not come up frequently enough to cycle ample environmental C02 into my garden. Making C02 supplementation a necessity. Then i would also be down the A/C rabbit hole as well.
So, the moral of the story - Let's be a bit more honest on equipment required to fully implement led into the garden for the way the mass of growers operate.
And also the true electrical costs of running all that equipment to support the use of led